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86 f-150 351w idle rough

first of all hello to everyone ---iam new
i have a 1986 f-150 351 ho 4bbl---was running rich -rebuilt carb and fixed that---went on a trip (600miles) started idling rough thought bad gas ran out changed filter no change ---so i thought cheap kit-- rebuilt carb again no change---cannot find a vacuum leak--runs good just real rough idle--- and hunts between 5&8 rpm in gear ---any suggestions on what to look for---? plugs, wires,cap & rotor all goood--new module also & coil---
thanks mike
 

countryboytn

'78 Bronco owner
First off Welcome to FTF!


I honestly can't tell you what to do for the idling, but somebody should be online before long that can help you. :beer:
 
Messed With It This Weekend---behind The Battry Pass Side Of Truck Is A Vacuum Manifold Type Of Thing With A Filter Hanging On The End Of A Hose---not Connected To Anything--sucking Lots Of Vacuum---plugged It Off And Alots Better---does That Give Anyone A Clue To What To Look For?
Thanks Mike
 

73F100Shortbed

That's how we roll!
5,937
320
NJ
That sounds to be your problem right there. A vacuum leak. If you plugged it and it got better it is the source of the vacuum leak. You may have some other smaller vacuum leaks as well. Check all your rubber hoses on the engine. Welcome to the site. And yes people do look at the site. Just takes some time to get the answers. I know I personally don't sit at the computer all day LOL.
 
no it is not a charcal can that is located at the front lower right of radiator---this is up on fender well right behind the battery---the scematics under the hood calls this a filter --mabe has a check ball in it that went south dont know but i plugged it and it is alot better---not like it used to be but at least it idles now
 
You could buy My 86 351W HO it idles fine when not in gear it needs a carb rebuild. It will work out just fine you'll see. we got a deal?
smilieIagree

sorry it sounds like a vac leak use some propane and a hose to find the leak it won't dry rot your hoses.

Chris

P.S. I am selling mine
 

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